Measurement of electrical and electromagnetic signals often involves distinguishing a target signal from noise. For devices that generate low output voltages, noise can easily overwhelm the target signal. Thermocouples, which are commonly used for temperature measurement in industry, often have output voltages in the millivolt range.
Thermocouples are sometimes used in electrically noisy environments, such as in the presence of induction heating supplies, that cause electromagnetic interference (EMI) noise to appear along with the thermocouple signal. The conventional approach for overcoming the problems caused by electrically noisy environments is to simply avoid making measurements in these environments. For example, induction heating supplies are typically turned off prior to making a thermocouple measurement.